Review Chapter 8- Skeletal Muscles Flashcards
Action of Deltoid
Extends arm when the posterior portion contracts abducts the arm when the lateral portion contracts and flexes the arm (at shoulder joint)
Action of extensor digitorum
Extends the phalanges
Action of gastrocnemius
Plantar flexes at ankle joint and flexes leg at knee joint (works with soleus)
Action of gluteus Maximus
Extends and laterally rotates thigh at the hip joint
Action of latissimus dorsi
Posterior arm muscle that extends the arm at the shoulder
Action of masseter
Main muscle that closes jaw
Action of orbicularis oris
Puckers lips
Action of rectus femoris
Only quadriceps muscle that flexes the thigh and extends leg
Action of triceps brachii
Antagonist of biceps brachii. Extends forearm at elbow/ extends arm at shoulder.
Action of zygomaticus major
Smiling :)
Antagonist
Muscle that produces an effect opposite of the prime mover
How muscles are named
Rectus- fibers parallel to midline Tranverse- fibers perpendicular to midline Minor- smallest of a set Maximus- largest of a set Biceps- two headed origin Triceps- three headed origin Orbicularis- circle shape Deltoid- triangle
Insertion
The end of a muscle attached to the movable bone
Origin
End of a muscle attached to the stationary bone
Synergist
Muscle that helps the prime mover function more efficiently
